1. Field of the Invention
The present invention relates generally to a television receiver, and more particularly, to a real-time compensation apparatus and method for a digital television receiver that determines a system time when the power supply is resumed, and controls the system according to the determined time.
2. Background of the Related Art
Generally, a television receiver (TV) that displays images by restoring broadcasting signals, which have been compressed into digital signals, through a decoder built in or outside the receiver is called a digital TV.
According to such a digital TV, since the whole process is digitally processed, any radio wave interference as in an analog TV does not occur, and a high picture quality and tone quality on the same level with a compact disc can be achieved. Also, since the bandwidth is effectively used in the digital TV, broadcasting channels more than those in the analog type TV can be secured in the same frequency band, and in theory, up to 100 TV broadcasting channels can be operated for each country.
Meanwhile, methods of effectively using the power supply in an electronic appliance such as the digital TV have been sought. Specifically, to solve the above-described problems, the conventional digital TV uses separate processors for input of keys, input through a remote control unit (RCU), and control of the power supply part. Also, the digital TV uses a real-time clock (RTC) for the present time and reservation information that uses a backup power supply, or uses a non-volatile memory such as E2PROM.
The digital TV performs a reserved recording in a manner that if a predetermined time elapses in a state that the digital TV is turned on, a video cassette recorder (VCR) that is an external appliance performs the recording in association with only an MPEG signal part of the digital TV, and if a user's program reservation time coincides with the present time, it performs the reserved recording function.
Hereinafter, the construction of the conventional digital TV will be explained with reference to the accompanying drawings.
FIG. 1 is a block diagram illustrating the construction of the conventional digital TV, and FIG. 2 is a block diagram illustrating the construction of the recording part of the digital TV.
The conventional digital TV for compensating for the real-time and reservation information includes two parts, i.e., a control part 10 and a driving part 20. The control part 10 comprises a remote control unit (RCU) input section 11, key input section 12, ROM 13, RAM 14, real-time clock (RTC) 16 for the real-time compensation, and first control section 17 in charge of controlling the power supply and operation according to the RCU input or key input. The driving part 20 comprises a second control section 21 for controlling a digital audio/video (A/V) output and a load 22, flash memory 24 and DRAM 23 for storing control signals from the second control section 21 or control signals from the control part.
In the conventional digital TV as constructed above, the first control section 17 receives a signal through the remote control unit (RCU) input section 11 and a key signal through the keypad 12, and transmits the signals to the second control section (i.e., CPU) 12 through a communication protocol. Also, the first control section 17 applies a reset signal 40 to the second control section 21 when the power is on.
The second control section 21 controls the load 22 so that the video and audio output is performed according to a signal self-produced and processed by the user's input signal and an MPEG signal transferred through a tuner that is one of controlled load devices.
Then, the second control section 21 stores the determined present time in the flash memory 24 using the user's input signal, signal processed according to the MPEG signal, and time date table (TDT)/TOT.
In the digital TV, the information on the presently broadcast programs is provided to the user using an event information table (EIT), and the time information can be obtained using the time date table (TDT) broadcast in synchronization with the EIT.
When the power is off, the first control section 17 updates the present time by using the RTC 16 or dividing the system clock, and compares the reserved time stored in the flash memory 24 with the present time. If the present time coincides with the reserved time, the first control section 17 turns on the power of the second control section to perform the reserved recording.
In performing the reserved recording, as shown in FIG. 2, the second control section 500 sends the MPEG signal of the tuner that is one of the controlled load devices to an MPEG decoder 510, so that the MPEG decoder 510 divides the MPEG signal into video and audio signals. If the reserved time according to the reservation signal elapses, a signal selection section 520 selects the channel signal desired by the user among the separated channel signals, and sends the selected channel signal to a SCART 530. The SCART 530 sends to a VCR 540 the video and audio signals of the selected channel, and a control signal for commanding the recording.
However, if the power of the second control section 21 is off, the information on the present time cannot be continuously updated. Consequently, the second control section 21 should be separately provided with the real time clock (RTC) having a backup power or a non-volatile memory that can store the reservation information of the user.
As described above, according to the conventional digital TV, the present time can be updated using the RTC having the self-backup power, but in case that the present time is updated by dividing the system clock without using the RTC, or the power supply is resumed due to the power failure or other reasons, there is no way to update the present time.